Method of preparing an organic adhered water-soluble knife-cut screen process printing stencil



Feb. 5, 1957 E. G. CONLEY 2,780,167

METHOD OF PREPARING AN ORGANIC ADHERED WATER-SOLUBLE KNIFECUT SCREEN PROCESS PRINTING STENCIL Filed Feb. 21, 1955 IN V EN TOR.

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United States Patent METHOD OF PREPARING AN ORGANIC AD- HERED WATER-SOLUBLE KNIFE-CUT SCREEN PROCESS PRINTING STENCIL Earl G. Conley, Tulsa, Okla.

Application February 21, 1955, Serial No. 489,611

1 Claim. (Cl. 101-1282) This invention relates to the art of stencil printing and surface ornamentation, and more particularly to the method and materials for preparing silk screens for use in printing designs by forcing inks, dye pastes and the like therethrough.

This application is a continuation in part of my copending application, Serial No. 326,668, filed December 18, 1952, which issued January 17, 1956, as Patent No. 2,731,356.

Sheets of waxed paper or films of cellophane, lacquers and the like for preparing stencils for silk screen printing have been in commercial use for some time, and in accordance with existing practices portions corresponding to the design to be printed are removed from the sheet by the use of a suitable solvent or by manually cutting the design therefrom and the remaining sheet then caused to adhere to the screen by the use of a hot iron or by means of a suitable solvent which renders the sheet tacky and capable of being adhesively secured to the screen.

In modern practice a film impervious to inks and the like to be used in the printing is mounted on a carrier and the design cut from the film. Once the film is cut the exposed surface thereof is placed in contact with fine silk fabric or other suitable material and a solvent applied to the surface of the film through the fabric, the solvent rendering the surface of the film tacky or adhesive and causing the entire film to adhere to the silk screen. The stencil film is usually mounted on the carrier sheet with a release compound or adhesive so that when the stencil film is adhered to the silk screen, the carrier sheet is peeled away from the adhered stencil film. The fine silk fabric is, of course, mounted upon a suitable frame under sufficient tension to maintain the fabric smooth. In using such stencils the object to be printed is placed under the silk screen and inks or the like arranged in a reservoir area at one end of the frame are pulled across the film with a squeegee, forcing the ink through the cutout portions of the film and through the silk screen onto the object to apply the design thereto.

The object of the present invention is to provide a solvent adhering type, knife-cut stencil which is watersoluble and may be removed from the silk mesh after use by noninflammable materials such as water; to provide such a stencil which permits use of fast evaporating solvents for adhering the film to the silk mesh; to provide a solvent adhering type knife-cut stencil composed principally of water-soluble cellulose ether, such as methylcellulose, and a suitable plasticizer and coloring pigment, the film being mounted on a transparent backing sheet with a release compound whereby the backing sheet is removable from the film after the film is cut and adhered to a silk screen mesh; to provide such a stencil film which when applied and -dried, is impervious to solvent action of all organic paint diluents and cleaners commonly used in the silk screen industry but is soluble in water, eliminating the use of expensive, explosively inflammable solvents and clean up thinners; and to provide ice a method and materials for preparing silk screens for use in printing designs which eliminates hazards due to use of inflammable materials in modern practices.

In the drawings:

Fig. l is a perspective view of a stencil film adhered to a fabric screen in a frame.

Fig. 2 is an enlarged section through a stencil film and carrier sheet adhered thereto.

Fig. 3 is an enlarged section through a stencil film and carrier sheet adhered thereto with cutout portions of the stencil film removed.

Fig. 4 is an enlarged section through the cut stencil film and carrier sheet applied to a fabric screen.

Fig. 5 is an enlarged section through a completed stencil screen with the film adhered thereto and the carrier sheet removed.

In accordance with the present invention the stencil film 1 is preferably composed of a cellulose ether which is water-soluble, for example methyl-cellulose, and a plasticizer, such as ethylene glycol or thiethanolamine, and suitable pigmentation may be added to the mixture of cellulose ether and plasticizer to provide desired color in the final film. The following are examples of the film composition:

Example 1 Parts Methyl-cellulose 8O Ethylene glycol 20 Example N Parts Methyl-cellulose Triethanolamine 20 The compositions, Examples 1 or II, or methyl-cellulose alone, are dissolved in water or a suitable organic solvent such as formamide, tetrachloroethane, bromoform, benzyl alcohol, ethylene chlorohydrin, ethyl glycollate, methyl salicylate, aniline, pyridine, quinoline or chloraniline. The solution may be applied by means of a coating machine, spraying or any other desired method to a carrier sheet 2 to form a film. Two or more coats of the solution may be used to obtain a relatively thicker film. The film is then suitably dried by passing it through a drying oven or otherwise.

The carrier sheet 2 is preferably cellulose acetate, glassine paper or other transparent material which, before coating with the cellulose ether solution, had previously been coated with a release compound 3 in the form of a rubber cement or other suitable material that will hold the cellulose ether film to the carrier sheet whereby the carrier sheet will serve as a backing sheet and permit the sheet to be peeled from the film after the film is adhered to a silk screen 4. The cellulose ether film 1 also may be suitably formed and then such film applied to a backing sheet 2 coated with a suitable release compound 3 or adhesive to hold the film on said backing sheet during cutting and application to a silk screen 4. The film and transparent backing sheet are relatively transparent when placed in contact with art work or other designs which the operator may wish to reproduce. The patterns, letters or designs are cut as at 5 through the cellulose film to the backing sheet by means of a sharp blade. Areas which are to be printed on the final stencil are lifted away from the backing sheet and discarded. When the design has been cut on the film a silk fabric 4 which is stretched on a stencil frame 6 is placed in close contact with the film 1 and an adhering solution applied to the silk fabric by means of a solvent dampened cloth, the solvent penetrating the silk fabric causing the surface of the film 1 contacting the silk fabric to become tacky and due to the pressure holding the film 1 in contact with the silk fabric 4, the film 1 is adhered to the fabric when the adhering solution has dried. The stencil frame is then-iifted and the transparent backing paper 2 is peeled away from the adhered stencil. The stencil adhering solution may be selected from formamide, tetrachloroethane,- bromoform, benzyl" alcohol, ethylene chlorohydrin, ethyl glycollate, methyl-salicylate, aniline, pyridine, quinoline, chloraniline, or a mixture of methylene chloride, ethylene dichloride and carbon tetrachloride. Methylene chloride, ethylene dichloride and carbon tetrachloride are not individually solvents of methyl-cellulose but are cosolvents when used in combination with methyl alcohol. There are other organic solvents of methyl-cellulose which could be used, however, it is preferable to utilize the most volatile solvents to obtain maximum rapidity of drying.

In the above examples, specific proportions are mentioned but while these proportions are very suitable, I do not restrict the present invention to these proportions It is believed obvious that I have provided a solvent adhering, water-soluble, knife-cut stencil film which reduces necessary time of preparing silk screens for use and also reduces the hazards connected therewith, as well as simplifying the removal of the stencil from the silk screen.

What I claim and desire to secure by Letters Patent is:

The method of forming a screen process printing stencil comprising a foraminous screen and a stencil film carried thereby, '-said---film being a-substantially-trans- Monthly, vol. 23, No. 2, February 1951.

parent water-soluble film of methyl-cellulose with a transparent backing sheet adhesively joined to but removable from one surface thereof, which method consists of cutting and removing portions corresponding to a design to be reproduced from the film, placing the surface or" the film opposite the backing sheet in engagement with the foraminous screen, applying a volatile References Cited in the file of this patent UNITED STATES PATENTS Barsky et al. May 5, 1942 OTHER REFERENCES Lacquer-proof Films, page 94 of the Graphic Arts (Copy available in Div. 17.) 

